TESTS OF WISCONSIN BUILDING STONE 



539 



fall away from the parent mass under very moderate pressure. 

 Loose particles at the surface are naturally more plentiful in the 

 case of sedimentary rocks such as sandstone than they are in the 

 case of igneous rocks or finely crystalline limesione. The loss 

 in weight due to alternate freezing and thawing will depend mainly 

 upon the manner in which the samples have been dressed and 

 the kind of stone tested. The experiments which I have per- 

 formed have demonstrated to my satisfaction that alternate 

 freezing and thawing for a period of thirty-five days results in 

 scarcely more than the removal of the loosened grains or frag- 

 ments from the surface. Any loss in weight which ma}/ be 

 partly accounted for by the manner of preparing the samples 

 does not indicate the extent to which the stone has been injured. 

 Loss in weight due to freezing and thawing was determined 

 for eighteen samples of granite from eleven different quarries. 

 The loss in weight in these cases did not exceed .05 of I per 

 cent, on a mass of about 350 to 360 grams. In the case of lime- 

 stone, in which twenty-one samples from eleven different quar- 

 ries were tested, the loss did not exceed .3 of I per cent., being, 

 as a rule, less than .1 of 1 per cent. The loss in weight of the 

 sandstone samples, of which twenty-four from twelve different 

 quarries were tested, did not exceed .62 of 1 per cent, and aver- 

 aged about .28 of 1 per cent. 



TABLE VI 



FREEZING AND THAWING TESTS 

 Loss per cent, of weight 



Granite and rhyolite : sixteen samples from 

 eleven different quarries 



Limestone : twenty-one samples from eleven 

 different quarries 



Sandstone: twenty-four samples from twelve 

 different quarries 



Such losses in weight are almost insignificant, and are valu- 

 able mainly in showing that the more loosely compacted 



